Dirac cones induced by accidental degeneracy in photonic crystals and zero-refractive-index materials
Dirac cones induced by accidental degeneracy in photonic crystals and zero-refractive-index materials
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DOI：
10.1038/nmat3030
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发表时间：
2011-08-01
期刊：
影响因子：
41.2
通讯作者：
Chan, C. T.
中科院分区：
文献类型：
--
作者：
Huang, Xueqin;Lai, Yun;Chan, C. T.
零折射率超材料是一种波不经历任何空间相变的材料，这种特殊的材料具有许多有趣的波操纵特性（1-10）。这些材料原则上可以使用包括金属谐振器（7）或手性夹杂物（11，12）的人造复合材料来实现，但是金属部件具有在高频下损害功能的损耗。如果我们能够单独使用λ来实现零折射率，这将是非常理想的。在这里，我们表明，通过采用偶然简并，可以设计和制造的介电光子晶体表现出狄拉克锥色散在有限频率的布里渊区的中心。除了狄拉克锥色散（13-19）固有的许多有趣的性质之外，我们可以使用有效介质理论将光子晶体与具有有效零介电常数和磁导率的材料联系起来。然后，我们数值和实验表明，在微波制度，这样的介电光子晶体与合理的介电常数操纵波，如果他们有近零的折射率在狄拉克点频率和附近。
A zero-refractive-index metamaterial is one in which waves do not experience any spatial phase change, and such a peculiar material has many interesting wave-manipulating properties(1-10). These materials can in principle be realized using man-made composites comprising metallic resonators(7) or chiral inclusions(11,12), but metallic components have losses that compromise functionality at high frequencies. It would be highly desirable if we could achieve a zero refractive index using dielectrics alone. Here, we show that by employing accidental degeneracy, dielectric photonic crystals can be designed and fabricated that exhibit Dirac cone dispersion at the centre of the Brillouin zone at a finite frequency. In addition to many interesting properties intrinsic to a Dirac cone dispersion(13-19), we can use effective medium theory to relate the photonic crystal to a material with effectively zero permittivity and permeability. We then numerically and experimentally demonstrate in the microwave regime that such dielectric photonic crystals with reasonable dielectric constants manipulate waves as if they had near-zero refractive indices at and near the Dirac point frequency.